Silicon photocathode functionalized with osmium complex catalyst for selective catalytic conversion of CO2 to methane

Solar-driven CO2 reduction to yield high-value chemicals presents an appealing avenue for combating climate change, yet achieving selective production of specific products remains a significant challenge. We showcase two osmium complexes, przpOs, and trzpOs, as CO2 reduction catalysts for selective CO2-to-methane conversion. Kinetically, the przpOs and trzpOs exhibit high CO2 reduction catalytic rate constants of 0.544 and 6.41 s−1, respectively. Under AM1.5 G irradiation, the optimal Si/TiO2/trzpOs have CH4 as the main product and >90% Faradaic efficiency, reaching −14.11 mA cm−2 photocurrent density at 0.0 VRHE. Density functional theory calculations reveal that the N atoms on the bipyrazole and triazole ligands effectively stabilize the CO2-adduct intermediates, which tend to be further hydrogenated to produce CH4, leading to their ultrahigh CO2-to-CH4 selectivity. These results are comparable to cutting-edge Si-based photocathodes for CO2 reduction, revealing a vast research potential in employing molecular catalysts for the photoelectrochemical conversion of CO2 to methane.


Datablock: przpOs
Bond precision: C-C = 0.0084 A; Wavelength=1.54178Cell: a=36.3907(9)b=10.9407(3)c=19.6531(5) alpha=90 beta=115.270(1)                          The EIS data are fitted using the equivalent circuits shown following: The constant phase elements (CPE) are used instead of the standard capacitance (C) in equivalent circuits due to the non-ideal capacitive behavior.C = CPE(ω max ) n/1 , where ω max is the frequency at which the imaginary value of the impedance has the maximum, and n is the empirical constant that describes the electrical behavior of CPE (CPE-T).

Figure S5 .
Figure S5.Electrochemical HER of [Os] complex.CV curves of 1.0 mM of przpOs

Figure S6 .
Figure S6.Element distribution diagram of the electrodes.(a) Cross-sectional

Figure S8 .
Figure S8.The element distribution of electrodes after PEC test.(a) Cross-

Figure S10 .
Figure S10.Simulated absorption and luminescence spectra.DFT calculation of

Figure S11 .
Figure S11.Optimized model structure and energy levels.The calculated

Figure S12 .
Figure S12.The orbital distribution and electrostatic potential of singlet and

Figure S21 .
Figure S21.Calculated intermediates for of direct protonation.przpOs (a) and
PLAT906_ALERT_3_C Large K Value in the Analysis of Variance ...... 2.0 ALERT level A = Most likely a serious problem -resolve or explain 0 ALERT level B = A potentially serious problem, consider carefully 9 ALERT level C = Check.Ensure it is not caused by an omission or oversight 8 ALERT level G = General information/check it is not something unexpected 3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 7 ALERT type 2 Indicator that the structure model may be wrong or deficient 4 ALERT type 3 Indicator that the structure quality may be low 2 ALERT type 4 Improvement, methodology, query or suggestion 1 ALERT type 5 Informative message, check * Eg,op optical band gaps calculated from the edge of MLCT absorption.**Eg,HL HOMO and LUMO levels from DFT calculation;

Table S3 .
Electrochemical CO 2 R activities of przpOs and trzpOs.

Table S4 .
PEC CO 2 R of Si/TiO 2 with and without [Os] complexes catalyst.

Table S6 .
EIS fitting data of p-Si/TiO 2 electrodes with and without [Os] catalyst